Circuit Breakers

Yes, but it may not be permitted for other reasons, depending on what you are trying to do.

Jim

Yes.

Yes, but be VERY careful. If you are feeding current to your panel from a generator, what you are doing is illegal and could result in extremely heavy penalties including conviction of manslaughter.

If you accidently feed your panel while it is connected to the utility's power line, their transmission lines will be energized even though they have the power switched off for service. The stepdown transformer that serves your house will act as a step-up transformer, etc. on up the line. This could and has caused fatal accidents.

A more likely event is that if you ever turn on your back-feed breaker while the utility's power is on and connected to your panel, you will immediately destroy your generator.

The normally approved method is for the service entrance and your generator to be connected to a transfer switch which then powers your panel either from the utility or from your generator but prevents accidental powering from both at the same time. If all circuits are not to be powered by the generator, then a breaker in the main panel can feed a sub-panel through a transfer switch. You can get manual or automatic transfer switches. The automatic ones will immediately switch to back-up power id the utility is off.